Global molecular epidemiology and genetic diversity of Fusarium, a significant emerging group of human opportunists from 1958 to 2015

Abstract

Fusarium is a rapidly emerging, multidrug-resistant genus of fungal opportunists that was first identified in 1958 and is presently recognized in numerous cases of fusariosis each year. The authors examined trends in global Fusarium distribution, clinical presentation and prevalence since 1958 with the assumption that their distributions in each region had remained unaltered. The phylogeny and epidemiology of 127 geographically diverse isolates, representing 26 Fusarium species, were evaluated using partial sequences of the RPB2 and TEF1 genes, and compared with AFLP fingerprinting data. The molecular data of the Fusarium species were compared with archived data, which enabled the interpretation of hundreds of cases published in the literature. Our findings indicate that fusariosis is globally distributed with a focus in (sub)tropical areas. Considerable species diversity has been observed; genotypic features did not reveal any clustering with either the clinical data or environmental origins. This study suggests that infections with Fusarium species might be truly opportunistic. The three most common species are F. falciforme and F. keratoplasticum (members of F. solani species complex), followed by F. oxysporum (F. oxysporum species complex).

Figure 1

A phylogenetic tree resulting from the RAxML analysis for the RPB2 and TEF1 genes. The total alignment length is 1302 bp. A maximum-likelihood analysis was performed using RAxML with non-parametric bootstrapping using 1000 replicates. The numbers above the branches are bootstrap support values ≥0.70. The outgroup was the epitype (ET) strain of F. dimerum CBS 108944.

Figure 2

Clustering of the amplified fragment length polymorphism banding pattern of Fusarium spp. combined with a sequence analysis of RPB2 and TEF1 constructed by Bionumerics v7.5 (Applied Maths). The dendrogram was generated using the Unweighted Pair Group Method with Arithmetic Mean algorithm.